I really think it's a toss up between Nikon and Canon. I'm not saying there aren't any other types of cameras professionals use, but it seems to be pretty evenly split (at least from what I've seen) between Nikon and Canon. Each photographer has their preference, I personally prefer the Canon Rebel T4i.

I have found that unsubscribing works pretty well in most cases. It hasn't eliminated all of my spam, but it has certainly cut down a large amount of it. I also have an email account that I only use rarely and am very select on who I give it out to, and that account never gets spam. Then I also have a more general email address that I use more frequently and casually so that if I do get spam it's more likely to go into that account rather than my main account.

Amazon is a great place to look at and possibly purchase cameras, but I know their prices aren't always the greatest. I know that Tiger Direct and Newegg, sell cameras as well, but I don't know if international buyers can purchase from their website, and if they ship internationally. It still might be worth having a look at their websites.